Why Do Cats Need Pre-Anesthetic Bloodwork?

What is pre-anesthetic bloodwork?

Pre-anesthetic bloodwork is a blood test that veterinarians recommend before a cat undergoes general anesthesia. While not compulsory in most veterinary practices, it is recommended because it provides the veterinarian information on the hydration status of the cat, organ function, blood sugar levels, and electrolyte balances.

Bloodwork can reveal a lot that cannot be picked up during a physical examination alone. These tests can provide the veterinarian with valuable information on the overall health of the cat, and how these findings will impact how the cat will respond to anesthesia and surgery.

Who needs pre-anesthetic bloodwork?

Ideally any cat who is undergoing anesthesia should have pre-anesthetic bloodwork. How detailed these tests are will differ depending on the age and health-status of the cat.

No pet owner or veterinarian wants a cat to hemorrhage on the operating table because of undiagnosed blood clotting disorders or liver disease, or have problems waking up from anesthesia because of impaired kidney or liver function. Cats with kidney disease are at increased risk of dehydration and electrolyte imbalances. All of these will be a factor before, during and after surgery.

When will the cat have pre-anesthetic bloodwork?

The veterinarian will schedule pre-anesthetic bloodwork in the days leading up to, or on the day of the surgery if the cat is in good health, and the surgery is routine (such as a healthy adolescent cat undergoing a spay or neuter) or if the cat requires immediate surgery (such as an accident or trauma). The results will enable the veterinarian to evaluate the following:

  • Can the cat safely handle an anesthetic and which anesthetic protocol is the safest?
  • If surgery is safe to proceed or is it safer to delay?
  • Will it be necessary to address medical conditions before surgery?
  • If it is not possible to delay surgery, are additional measures necessary such as IV fluids or have blood or plasma on emergency standby?

What is being tested?

Tests can vary from practice to practice and cat to cat but usually consist of three tests, the biochemical profile, electrolytes, and a complete blood count. These tests will reveal how the liver and kidneys are functioning as it is their job to metabolise anesthesia as well as electrolyte levels which can be out of balance in cats with kidney disease, blood cell counts, to check for anemia (low red blood cell count), possible blood clotting disorders and infection or inflammation (elevated white blood cell count).

Biochemical profile

  • Alanine transaminase (ALT)
  • Aspartate transaminase (AST)
  • Alkaline phosphatase (ALP)
  • Blood Urea Nitrogen (BUN)
  • Calcium (CA)
  • Cholesterol (CHOL)
  • Creatinine
  • Glucose
  • Total protein

Complete blood count

  • Red blood cell count (RBC)
  • Haemoglobin (Hb)
  • White blood cell count (WBC)
  • Platelet (thrombocytes) count


  • Sodium
  • Potassium
  • Chloride

Reasons to delay surgery

Some findings may lead to the decision to postpone surgery, especially for cats undergoing elective procedures, such as spay/neuter or routine dental work.

  • Elevated white blood count indicates an infection, antibiotic therapy can be initiated to treat the infection before surgery
  • Low blood platelets
  • Poor liver function
  • Severe dehydration

Does the test hurt?

The test is uncomfortable when the veterinarian takes blood from the jugular vein, but it should not hurt.

How much does it cost?

This will vary from practice to practice as well as the age of the cat. Some surgeries may not run as many tests on a young cat compared to a middle-aged or senior cat. At the date of publication, pre-anesthetic bloodwork for my dog (who is about to undergo surgery) is $95 Australian dollars.

The small additional cost is worth the peace of mind the tests provide. Results also serve as a useful benchmark for future diagnostics and provide the opportunity to address underlying medical conditions often in their early stages, which provides a better outcome.


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio